Microwave ovens for the production of substances and/or components, in particular ceramic components and/or dental ceramics have been known for some time. Reference is made, by way of example, to EP 1 060 713 A2. Also the use of susceptors for microwaves has been known for a long time, for instance from DE-OS 2 021 901, which mentions the use of susceptors as well as heating via microwaves.
Different materials which can be used for microwave heating devices are mentioned in DE 37 03 163 A1 and corresponding U.S. Pat. Nos. 4,800,247 and 5,057,659, which US patents are hereby incorporated by reference. The susceptor mentioned therein serves for absorbing microwave radiation.
In the heat treatment of dental ceramics with the help of microwaves, it is essential for the susceptors used to provide coupling over a wide area. This requirement can be fulfilled comparatively well with the help of silicon carbide which, moreover, has a thermal stability of >2000° C., and therefore securely covers the temperature range desired for the heat treatment of ceramics, in particular of dental ceramics.
The silicon carbide qualities used so far, however, often have impurities resulting from the production process, for instance of vanadium or manganese etc., which may, for example, lead to discolorations of the objects to be heat-treated.
In particular with large ceramic components and/or multi-member dental bridges or larger dental replacement parts, it is essential for the heat to be spread uniformly and therefore for heat-induced stresses and the resulting possible formation of microfissures to be avoided in the objects to be heat-treated.